# PG throws could not resize shared memory segment error
**URL:** https://meta.discourse.org/t/pg-throws-could-not-resize-shared-memory-segment-error/84744
**Category:** Self-hosting
**Created:** [April 6, 2018, 4:52pm UTC](https://meta.discourse.org/t/pg-throws-could-not-resize-shared-memory-segment-error/84744 "2018-04-06T16:52:20Z")
**Posts on this page:** 7
**Page:** 1
### Author:  [@Gunnar](https://meta.discourse.org/u/Gunnar)
#### Post date: [April 6, 2018, 4:52pm UTC](https://meta.discourse.org/t/pg-throws-could-not-resize-shared-memory-segment-error/84744/1 "2018-04-06T16:52:21Z")
After upgrading (with ‘launcher rebuild app’ times two) to Postgres 10, we’ve started seeing errors like this in /logs:
```plaintext
Failed to handle exception in exception app middleware :
PG::DiskFull: ERROR: could not resize shared memory segment "/PostgreSQL.682207201" to 283432 bytes: No space left on device :
SELECT "topics"."id" AS t0_r0, "topics"."title" AS t0_r1, "topics"."last_posted_at" AS t0_r2, …
```
Ideas? Looks like PG is unable to increase the size of a shared memory segment, can this be tuned somewhere?
---
### Author:  [@supermathie](https://meta.discourse.org/u/supermathie)
#### Post date: [April 6, 2018, 5:21pm UTC](https://meta.discourse.org/t/pg-throws-could-not-resize-shared-memory-segment-error/84744/3 "2018-04-06T17:21:09Z")
This is due to the fact that docker by default [restricts shared memory size](https://www.postgresql.org/message-id/CAEepm%3D2wXSfmS601nUVCftJKRPF%3DPRX%2BDYZxMeT8M2WwLSanVQ%40mail.gmail.com) to 64MB which makes pg10 run afoul of this limitation when doing a number of scatter/gather jobs in parallel:
```plaintext
Outside the container:
supermathie@host: ~ $ df -h /dev/shm
Filesystem Size Used Avail Use% Mounted on
none 63G 1.2M 63G 1% /run/shm
Inside the container:
supermathie@host: ~ $ docker exec -it postgres-master df -h /dev/shm
Filesystem Size Used Avail Use% Mounted on
shm 64M 8.0K 64M 1% /dev/shm
```
You should raise the limit when launching the postgres container by including the `--shm-size=1g` parameter.
We’ll look at fixing this in the launcher.
(or as the link suggests, disable parallelism in pg10 with `max_parallel_workers_per_gather = 0`)
---
### Author:  [@Gunnar](https://meta.discourse.org/u/Gunnar)
#### Post date: [April 6, 2018, 6:37pm UTC](https://meta.discourse.org/t/pg-throws-could-not-resize-shared-memory-segment-error/84744/5 "2018-04-06T18:37:33Z")
> [@supermathie](#):
>
> You should raise the limit when launching the postgres container by including the --shm-size=1g parameter.
>
> We’ll look at fixing this in the launcher.
>
> (or as the link suggests, disable parallelism in pg10 with max\_parallel\_workers\_per\_gather = 0)
Thanks. How would I do either of those? I searched, found this post ([Starting Discourse on a Specific Docker Network - #3 by dlynch158](https://meta.discourse.org/t/starting-discourse-on-a-specific-docker-network/49401/3)) and following the example added the following line to my app.yml:
`docker_args: "--shm-size=1g"`
Then ran launcher rebuild app. That didn’t make any difference though, shm is still 64M inside the container.
Thanks,
Gunnar
---
### Author:  [@supermathie](https://meta.discourse.org/u/supermathie)
#### Post date: [April 6, 2018, 6:40pm UTC](https://meta.discourse.org/t/pg-throws-could-not-resize-shared-memory-segment-error/84744/6 "2018-04-06T18:40:23Z")
You need to make sure that’s on your data container.
EDIT:
OK, adding the following:
```plaintext
docker_args: "--shm-size=512m"
```
to your `app.yml` (if all-in-one) or `data.yml` (if separate pg) containers should prevent this from happening. I’ve left the shm size at a conservative 512MB.
Or if you pull latest and relaunch it’ll now start the container with that shm size.
@tgxworld I’ve pushed a change that changes the launcher to always launch with 512MB SHM size under bootstrap or run. Should be safe.
---
### Author:  [@Gunnar](https://meta.discourse.org/u/Gunnar)
#### Post date: [April 6, 2018, 8:53pm UTC](https://meta.discourse.org/t/pg-throws-could-not-resize-shared-memory-segment-error/84744/7 "2018-04-06T20:53:59Z")
Thanks for adding that to launcher, shm is now 512m inside our container (and yes, we have just the one).
Just FYI, for some reason, adding the
`docker_args: "--shm-size=512m"`
line to app.yml (and rebuilding) did nothing.
Thanks!
Gunnar
---
### Author:  [@supermathie](https://meta.discourse.org/u/supermathie)
#### Post date: [April 6, 2018, 8:55pm UTC](https://meta.discourse.org/t/pg-throws-could-not-resize-shared-memory-segment-error/84744/8 "2018-04-06T20:55:37Z")
Weird - it did when I tested it.
But that’s OK, launcher just takes care of it now.
---
### Author:  [@JammyDodger](https://meta.discourse.org/u/JammyDodger)
#### Post date: [June 8, 2024, 12:37pm UTC](https://meta.discourse.org/t/pg-throws-could-not-resize-shared-memory-segment-error/84744/9 "2024-06-08T12:37:37Z")
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